1. Field of the Invention
The present invention relates to a finite linear motion rolling guide unit which is used under compound load in a precise assembling work of electronic parts or the like.
2. Description of the Related Background Art
Conventional finite linear motion rolling guide units disclosed in, for instance, U.S. Pat. Ser. Nos. 3,857,618, 4,662,763, 4,610,488, and 4,253,709 and Japanese Patent Application Disclosure Nos. 38216-1986 and 266823-1986 and the like have the following drawbacks. When such a rolling guide unit is operated by the reciprocating motion at a relatively high speed, a deviation of ball assemblies with holders occurs between the side surface of a track member and the inner side surface of a sliding member. Such a deviation phenomenon of the holders occurs because the positions of the ball assemblies are gradually deviated in one direction due to the inertial forces of the holders which hold the balls. Finally, the ball assembly collides with a stopper for the holder and, in this portion, an abnormal abrasion occurs or a sliding abrasion due to the deviation of the balls occurs. Thus, such a deviation phenomenon becomes causes of the burning of the unit and the short life thereof.
To prevent such a deviation, hitherto, a method whereby the surface of each ball is made rough or a method whereby a rack is formed on the track member and a pinion is attached to the holder, or the like has been used. However, such a method is still insufficient for prevention of the deviation or causes the costs to be increased due to various attached members. A proper method of solving the deviation is not developed yet.